131 lines
6.0 KiB
HTML
131 lines
6.0 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This file documents the GNU Assembler "as".
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Copyright (C) 1991-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled "GNU Free Documentation License".
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-->
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<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Using as: Statements</title>
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<meta name="description" content="Using as: Statements">
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<meta name="keywords" content="Using as: Statements">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Syntax.html#Syntax" rel="up" title="Syntax">
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<link href="Constants.html#Constants" rel="next" title="Constants">
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<link href="Symbol-Intro.html#Symbol-Intro" rel="prev" title="Symbol Intro">
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<style type="text/css">
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<!--
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a.summary-letter {text-decoration: none}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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div.indentedblock {margin-left: 3.2em}
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div.lisp {margin-left: 3.2em}
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div.smalldisplay {margin-left: 3.2em}
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div.smallexample {margin-left: 3.2em}
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div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
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div.smalllisp {margin-left: 3.2em}
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kbd {font-style:oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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pre.menu-comment {font-family: serif}
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pre.menu-preformatted {font-family: serif}
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pre.smalldisplay {font-family: inherit; font-size: smaller}
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pre.smallexample {font-size: smaller}
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pre.smallformat {font-family: inherit; font-size: smaller}
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pre.smalllisp {font-size: smaller}
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span.nocodebreak {white-space:nowrap}
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span.nolinebreak {white-space:nowrap}
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span.roman {font-family:serif; font-weight:normal}
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span.sansserif {font-family:sans-serif; font-weight:normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Statements"></a>
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<div class="header">
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<p>
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Next: <a href="Constants.html#Constants" accesskey="n" rel="next">Constants</a>, Previous: <a href="Symbol-Intro.html#Symbol-Intro" accesskey="p" rel="prev">Symbol Intro</a>, Up: <a href="Syntax.html#Syntax" accesskey="u" rel="up">Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Statements-1"></a>
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<h3 class="section">3.5 Statements</h3>
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<a name="index-statements_002c-structure-of"></a>
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<a name="index-line-separator-character"></a>
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<a name="index-statement-separator-character"></a>
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<p>A <em>statement</em> ends at a newline character (‘<samp>\n</samp>’) or a
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<em>line separator character</em>. The line separator character is target
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specific and described in the <em>Syntax</em> section of each
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target’s documentation. Not all targets support a line separator character.
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The newline or line separator character is considered to be part of the
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preceding statement. Newlines and separators within character constants are an
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exception: they do not end statements.
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</p>
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<a name="index-newline_002c-required-at-file-end"></a>
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<a name="index-EOF_002c-newline-must-precede"></a>
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<p>It is an error to end any statement with end-of-file: the last
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character of any input file should be a newline.
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</p>
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<p>An empty statement is allowed, and may include whitespace. It is ignored.
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</p>
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<a name="index-instructions-and-directives"></a>
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<a name="index-directives-and-instructions"></a>
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<p>A statement begins with zero or more labels, optionally followed by a
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key symbol which determines what kind of statement it is. The key
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symbol determines the syntax of the rest of the statement. If the
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symbol begins with a dot ‘<samp>.</samp>’ then the statement is an assembler
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directive: typically valid for any computer. If the symbol begins with
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a letter the statement is an assembly language <em>instruction</em>: it
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assembles into a machine language instruction.
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Different versions of <code>as</code> for different computers
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recognize different instructions. In fact, the same symbol may
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represent a different instruction in a different computer’s assembly
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language.
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</p>
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<a name="index-_003a-_0028label_0029"></a>
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<a name="index-label-_0028_003a_0029"></a>
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<p>A label is a symbol immediately followed by a colon (<code>:</code>).
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Whitespace before a label or after a colon is permitted, but you may not
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have whitespace between a label’s symbol and its colon. See <a href="Labels.html#Labels">Labels</a>.
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</p>
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<p>For HPPA targets, labels need not be immediately followed by a colon, but
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the definition of a label must begin in column zero. This also implies that
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only one label may be defined on each line.
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</p>
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<div class="smallexample">
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<pre class="smallexample">label: .directive followed by something
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another_label: # This is an empty statement.
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instruction operand_1, operand_2, …
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</pre></div>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Constants.html#Constants" accesskey="n" rel="next">Constants</a>, Previous: <a href="Symbol-Intro.html#Symbol-Intro" accesskey="p" rel="prev">Symbol Intro</a>, Up: <a href="Syntax.html#Syntax" accesskey="u" rel="up">Syntax</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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